diff --git a/nashorn/src/jdk/nashorn/internal/runtime/DebuggerSupport.java b/nashorn/src/jdk/nashorn/internal/runtime/DebuggerSupport.java
index 9f7783eac06..c288a963321 100644
--- a/nashorn/src/jdk/nashorn/internal/runtime/DebuggerSupport.java
+++ b/nashorn/src/jdk/nashorn/internal/runtime/DebuggerSupport.java
@@ -243,7 +243,7 @@ final class DebuggerSupport {
             return value.toString();
 
         case STRING:
-            return escape((String)value);
+            return escape(value.toString());
 
         case NUMBER:
             return JSType.toString(((Number)value).doubleValue());